Police officers patrol a swampy area in Fox Lake, Ill., during a manhunt after an officer was shot and killed while pursuing a group of suspicious men, Tuesday, Sept. 1, 2015. Authorities in Fox Lake, 55 miles north of Chicago,  have notified a number of other law enforcement agencies to ask for assistance, including the FBI, which is sending agents to help in the investigation. (Stacey Wescott/Chicago Tribune via AP) MANDATORY CREDIT CHICAGO TRIBUNE; CHICAGO SUN-TIMES OUT; DAILY HERALD OUT; NORTHWEST HERALD OUT; THE HERALD-NEWS OUT; DAILY CHRONICLE OUT; THE TIMES OF NORTHWEST INDIANA OUT; TV OUT; MAGS OUT; NO SALES    ORG XMIT: ILCHT103 Photo: Stacey Wescott / Chicago Tribune